uires gradual and nearly uniform
introduction, possibly more sudden extermination,--subsidence of
continent of Australia &c., &c.

{116} The sudden appearance of groups of allied species in the
lowest known fossiliferous strata is discussed in the _Origin_, Ed.
i. p. 306, vi. p. 446. The gradual appearance in the later strata
occurs in the _Origin_, Ed. i. p. 312, vi. p. 453.

Our theory requires that the first form which existed of each of the
great divisions would present points intermediate between existing ones,
but immensely different. Most geologists believe Silurian{117} fossils
are those which first existed in the whole world, not those which have
chanced to be the oldest not destroyed,--or the first which existed in
profoundly deep seas in progress of conversion from sea to land: if they
are first they <? we> give up. Not so Hutton or Lyell: if first
reptile{118} of Red Sandstone <?> really was first which existed: if
Pachyderm{119} of Paris was first which existed: fish of Devonian:
dragon fly of Lias: for we cannot suppose them the progenitors: they
agree too closely with existing divisions. But geologists consider
Europe as <?> a passage from sea to island <?> to continent (except
Wealden, see Lyell). These animals therefore, I consider then mere
introduction <?> from continents long since submerged.

{117} Compare _Origin_, Ed. i. p. 307, vi. p. 448.

{118} I have interpreted as _Sandstone_ a scrawl which I first read
as _Sea_; I have done so at the suggestion of Professor Judd, who
points out that "footprints in the red sandstone were known at that
time, and geologists were not then particular to distinguish
between Amphibians and Reptiles."

{119} This refers to Cuvier's discovery of _Palaeotherium_ &c. at
Montmartre.

Finally, if views of some geologists be correct, my theory must be given
up. [Lyell's views, as far as they go, are in _favour_, but they go so
little in favour, and so much more is required, that it may <be> viewed as
objection.] If geology present us with mere pages in chapters, towards
end of <a> history, formed by tearing out bundles of leaves, and each page
illustrating merely a small portion of the organisms of that time, the
facts accord perfectly with my theory{120}.

{120} This simile is more fully given in the _Origin_, Ed. i. p.
310, vi. p. 452. "For my part, following out Lyell's metaphor, I
look